Device to prevent rocking of tables

ABSTRACT

A stabilising device for a table or the like article includes a cam device ( 10 ) which is rotatable on an axle ( 18 ) to engage the surface on which the table is located to prevent it from rocking. The cam is mounted on the table leg by a bracket ( 14 ). The cam may be locked in the desired position.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a device for stabilizing tables in particular and preventing the rocking of such articles located on uneven surfaces or having legs of slightly different length.

BACKGROUND ART

Restaurateurs in particular, are constantly frustrated by having to try to stabilize tables which rock due to the unevenness of floors. Tables must be moved constantly for cleaning purposes and to re-arrange settings for different-sized groups. Typically, the problem is attempted to be solved using wedges in the form of folded paper or even wooden wedges, but most often this achieves very little. A slight movement of the table requires readjustment, adding to the frustration of waiters, patrons and the like.

It is an object of this invention to provide a stabilizer which is not only effective, but inexpensive to manufacture, easy to operate and further which is required to be fitted to only one leg of a table to be stabilized.

DISCLOSURE OF THE INVENTION

According to the invention, a device for stabilizing tables, chairs and other similar articles includes a cam means mountable on a leg of the article and being movable from a first position which, when the other legs of the article are flush with the surface upon which it is located, is spaced apart from the surface, and a second position in which a portion of the cam means is in contact with the surface, such that the article is not susceptible to rocking when the cam means is in the second position.

In the preferred form of the invention, the cam means is mounted at the lower end of the leg, and rotation thereof causes the leg to be raised or lowered; and means to releasably lock the cam in a desired position is provided.

In the one form of the invention, the cam comprises a wheel or pair of wheels. The wheel operates as a cam by engaging a transverse shaft (wheel axle) at a point remote from the centre of the wheel. The eccentric attachment causes raising or lowering of the leg upon rotation of the wheel.

The cam is preferably non-reversible, being rotatable in one direction only. This enables the cam to be locked in the desired position.

In the preferred form of the invention, the wheel has braking means associated with the axle. The brake means preferably comprises a pawl and the axle comprises a ratchet-wheel Rotation of the wheel about the axle in the clockwise direction is uninhibited, but attempted rotation in the anti-clockwise direction results in immediate engagement of the pawl with the inclined teeth of the ratchet-wheel to act as a brake.

The ratchet-wheel is housed within the hollow body of the wheel and is rotatable about the wheel hub. Integral with the ratchet wheel is a central cylindrical shaft which forms the wheel axle which extends through the wheel hub, through an opening to engage a mounting bracket.

In the preferred form of the invention, the mounting bracket for attaching the device to the leg of the article is a right-angled bracket, one portion of which is securable to the leg of the table etc., the other providing a mounting point for the eccentric wheel. A mounting screw fastens the bracket to a wheel axle.

In this form, mounting screw engages a central bore in the axle, the outer end of the axle including a polygonal protrusion for engaging a complimental opening in the bracket. This ensures that the axle is fixed to the bracket and hence the table leg, with the wheel rotating about the axle. The bracket is easily screwed or otherwise fastened to the table leg.

In an alternative form of the invention, the cam comprises a two-wheeled castor having an eccentrically located transverse axle, the wheel including a weighted section biasing the wheel towards a particular orientation and enabling gravity-assisted rotation of the wheel.

This form of the invention may be secured to the leg of the table or other article by means of a suitable clamp or the like which is in turn secured to a shaft including at the lower end thereof a short transverse tubular section for receiving the transverse shaft of the cam. It is important to note that the angle of the leg does not affect the operation of the device in that regardless of whether the leg is vertical, horizontal or at an angle therebetween, the cam will always engage the ground at the lowest point in its rotation path. The transverse tubular section is provided with a clutch bearing with which the transverse shaft of the wheel is rotatable in one direction only.

In use, the device is fitted to one leg of a table for example. When the table is located in a desired position and it is found that the table is not stable due to unevenness of the floor, the cam wheel is rotated clockwise into a position in which the rocking of the table is eliminated as the cam has effectively filled the gap between the floor and the bottom of the leg to which it is attached. At this point the cam cannot be rotated in the reverse direction due to the non-reversible nature of the cam.

The diameter of the wheel will determine the size of the leg lengthening or put differently, the size of the gap which the device will take up to eliminate unsteadiness. The advantage of the device is that incremental adjustments are possible down to fractions of a millimetre ensuring that the exact height adjustment required is achievable.

The device of the invention may be retro-fitted to an existing table or may be supplied integral with a table Thus, according to a second aspect of the invention, a table or the like includes a cam means attached to at least one leg thereof, the cam means being movable from a first position which, when the other legs of the article are flush with the surface upon which it is located, is spaced apart from the surface, and a second position in which a portion of the cam means is in contact with the surface, such that the article is not susceptible to rocking when the cam means is in the second position.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the preferred form of the invention is described below with reference to the accompanying drawings in which:

FIG. 1(a) is an isometric view of the legs of a 4-legged table fitted with a device according to the invention;

FIGS. 1(b) and 2 are magnified isometric side views of a device of FIG. 1 in minimum and maximum leg lengthening positions respectively;

FIGS. 3 and 4 are identical views to FIGS. 1 and 2 but with the cover plate removed;

FIG. 5 is a side view with the brake disengaged;

FIGS. 6 and 7 are side views of the device with the brakes engaged in the position of FIGS. 1 and 3; 2 and 4 respectively;

FIGS. 8 and 9 are rear views of the device in the position of FIGS. 1, 3 and 2, 4 respectively,

FIG. 10 is an exploded isometric view of the device;

FIG. 11 is a magnified isometric view of the front of the wheel, ratchet-wheel and brake;

FIG. 12 is a rear view of the components of FIG. 11;

FIG. 13 is a front isometric view of the bracket and cover plate;

FIG. 14 is a rear isometric view of the components of FIG. 13.

DESCRIPTION OF THE BEST MODE

In the drawings, a device according to the invention comprises an eccentric wheel 10 fastened at or near the base of a table leg 12. The eccentric wheel operates as a cam and when rotated, effectively raises the table leg by any desired amount between the minimum and maximum positions shown in FIGS. 1 and 2 respectively. The wheel is rotatable in one direction only, namely clockwise. Attempted rotation in an anti-clockwise direction results n a brake engaging. This allows the device to be set at the correct position to prevent it from rocking.

The wheel is mount on a table leg using a bracket 14 fastened to the leg by a bolt or screw. Where the table has built-in levellers, one may be removed and replaced with the device of the invention. Mounting screw 16 fastens the bracket to the wheel axle 18 which protrudes from the rear of the wheel hub 20. The rear of the axles has a central bore 22 of receiving the mounting screw and is further square in section. The bracket includes an identical square hole 24 for engaging the square rear 23 of the axle, preventing rotation of the axle relative to the bracket and hence the table leg. As shown in FIG. 12, the axle 18 comprises a central cylindrical shaft 26 affixed at the inner end to a ratchet-wheel 28 of greater diameter than the cylindrical shaft 26. The channel formed between the shaft and the ratchet-wheel fits onto the wheel hub 20 and rotates therearound.

The ratchet-wheel 28 is housed within the hollow body of the wheel 10. The braking mechanism associated with the axles comprises a pawl 30 pivotally mounted at 32 and which includes a bracing element 34. This arrangement permits inhibited clockwise rotation of the wheel about the axle, but rotation in an anti-clockwise direction causes immediated engagement of teeth 36 of the brake with the teeth 38 of the ratchet-wheel.

As can be seen from FIGS. 3 through 7, the wheel 10 is mounted eccentrically, the wheel axle 18 and the wheel hub 20 being located between the centre of the wheel and the edge thereby. Rotation thereof consequently follows a path which causes the distance from the centre of the axle 18 to the ground (distance A-A in FIG. 5) to progressively increase to a maximum measured by distance B-B in FIGS. 6 and 7. This rotation therefore effectively increases the gap between the bottom of the leg 12 and the floor to stabilise the table and prevent it from rocking. This is further illustrated by comparing the distance between the base of the leg 40 and the base of the wheel 42 (distances X-Y and X-Z in FIGS. 8 and 9). The rotation may be stopped and locked at any point between the positions shown in FIGS. 3 and 4 to effectively reduce the gap by the amount required to stabilise the table. Further clockwise rotation towards the starting point shown in FIG. 3 results in the table become progressively less stable.

DESCRIPTION OF ALTERNATIVE MODE OF THE INVENTION

FIGS. 15, 16 and 17 are isometric front views of the device according to the invention in three different positions equating to three (of many) possible height adjustments;

FIG. 18 is an exploded isometric view of the device;

FIG. 19 is an isometric view of the table with the device attached to one leg; and

FIG. 20 is a magnified view of the lower end of the table leg.

In FIGS. 15 to 18, a device 50 according to the invention comprises a two-wheeled castor having an eccentrically located transverse axle 52 to which is attached a vertical shaft 54. The vertical shaft is clamped (FIGS. 19 and 20) to a leg 56 of a table 58 to be stabilized. In this illustration the table leg is vertical and hence shaft 54 is vertically orientated. Should the table leg be horizontal or angled, the shaft would simply be orientated at a similar angle for ease of clamping.

At least one wheel of the castor includes a weighted segment 60 in the form of a metal insert which biases the wheel to the desired orientation under the action of gravity.

The castor acts as a non-reversible cam which only turns in a clock-wise direction and accordingly, once the wheels have been rotated into the required location in which the effective length of the table leg has been increased, the wheels cannot roll backwards and reverse the leg extension. The non-reversible motion of the cam is achieved by mounting the transverse axle, which may be provided in two sections 52 a and 52 b, within a clutch bearing 64 provided within the tubular section 66 at the base of shaft 54. The clutch bearing permits rotation in one direction only.

In FIGS. 15 to 17, three different positions or orientations of the device are illustrated. In FIG. 1, the transverse shaft or axles 52 of the device is located at the top of the wheel and hence in a position to give the greatest height extension In FIG. 16, the axle is approximately at the midpoint of the wheel and the extension provided is approximately half of that of FIG. 1. In FIG. 17, however, the extension given by the device is minimal.

In FIGS. 19 and 20, the device of the invention is shown locked in a position in which the table 58 is stabilized, level and will not rock. Clamp 62 mounts the device onto the table leg 56. 

1. A device for stabilizing tables, chairs and other similar articles characterised in that it includes a cam means mountable on a leg of the article and being movable from a first position which, when the other legs of the article are flush with the surface upon which it is located, is spaced apart from the surface, and a second position in which a portion of the cam means is in contact with the surface, such that the article is not susceptible to rocking when the cam means is in the second position.
 2. A device according to claim 1 characterised in that the cam means is mounted at the lower end of the leg, and rotation thereof causes the leg to be raised or lowered.
 3. A device according to claim 1 characterised in that the cam is non-reversible, being rotatable in one direction only.
 4. A device according to claim 1, characterised in that means to releasably lock the cam in a desired position is provided.
 5. A device according to claim 1, characterised in that the cam comprises an eccentric wheel, the eccentric attachment of the wheel axle to the wheel resulting in raising and/or lowering of the leg upon rotation of the wheel.
 6. A device according to claim 5 characterised in that the wheel has braking means associated with the wheel axle.
 7. A device according to claim 6 characterised in that the braking means comprises a pawl and the axle comprises a ratchet-wheel.
 8. A device according to claim 7 characterised in that rotation of the wheel about the wheel axle is the clock-wise direction results in immediate engagement of the pawl with the inclined teeth of the ratchet-wheel to act as a brake.
 9. A device according to claim 7 characterised in that the ratchet-wheel is housed within the hollow body of the wheel and is rotatable about the wheel hub, the ratchet-wheel including an integral central cylindrical shaft which forms the wheel axle which extends through the wheel hub, through an opening to engage a mounting bracket.
 10. A device according to claim 1 characterised in that the cam means is mountable of the leg of the article by means of a right-angled mounting bracket, one portion of which is securable to the leg of the article, the other providing a mounting point for the eccentric wheel.
 11. A device according to claim 10 characterised in that the bracket is attached to the wheel axle by means of a mounting screw.
 12. A device according to claim 11 characterised in that the mounting screw engages a central bore in the axle, the outer end of the axle including a polygonal protrusion for engaging a complimental opening in the bracket.
 13. A device according to claim 5 characterised in that the cam comprises a two-wheeled castor having an eccentrically located transverse axle, the wheel including a weighted section biasing the wheel towards a particular orientation and enabling gravity-assisted rotation of the wheel.
 14. A device according to claim 13 characterised in that the castor is secured to the leg of the table or other article by means of a suitable clamp or the like which is in turn secured to a shaft including at the lower end thereof a short transverse tubular section for receiving the transverse shaft of the cam.
 15. A device according to claim 14 characterised in that the transverse tubular section is provided with a clutch bearing with which the transverse shaft of the wheel is rotatable in one direction only.
 16. A table or the like article characterised in that it includes a cam means attached to at least one leg thereof, the cam means being movable from a first position which, when the other legs of the article are flush with the surface upon which it is located, is spaced apart from the surface, and a second position in which a portion of the cam means is in contact with the surface, such that the article is not susceptible to rocking when the cam means is in the second position.
 17. A device substantially as described with reference to the accompanying drawings.
 18. A device according to claim 2 characterised in that the cam is non-reversible, being rotatable in one direction only.
 19. A device according to claim 2, characterised in that means to releasably lock the cam in a desired position is provided.
 20. A device according to claim 3, characterised in that means to releasably lock the cam in a desired position is provided. 